When producer Colin Barr approached me about writing a factual drama for TV about George Best, I was sceptical.

The George Best I knew was a tabloid headline, one of those slightly dated 1970s figures who went out with beauty queens and drank too much.

Before I started this, I thought that George Best had been simply elevated to greatness because he was one of our own. The Sixties superstar footballer was lost to me.

I didn’t know he was great — really great. I was surprised to discover that Pele, considered by many to be the world’s best footballer, ranked George as the better player.

But George was a world-class great who rarely got to play world class football. I realised that the opportunities weren’t there for him to build a real legacy in football. He was an extraordinary talent forced to limit himself by playing in circumstances often too ordinary for him.

But in itself this wasn’t a story I was interested in telling. I wasn’t interested in writing a piece about football, with last-minute goals and winning games against the odds. And I didn’t think there was any story to tell about the drinking and womanising. We all knew this anyway — why rehash old history?

Of course, the story of George the footballer and George the celebrity playboy was only the half of it. I hadn’t known much about his background except that he was from Belfast. And as I read more, I was impressed by how well he had managed not to talk about politics and religion in a country full of both. I realised I hadn’t even known what religion he was.

For me the real bolt out of the blue was finding out that his mother Ann was also an alcoholic. Not only that but that she had been teetotal until she reached her mid-40s — and was dead within 10 years of alcohol-related heart disease.

There’s a huge question there. Ann had passed both her beauty and her sporting ability on to George. Was the darker part of her legacy to him a genetic predisposition to alcoholism? Was George an alcoholic because of his mother? Could it be that simple?

Ann had lived a very normal life up until George’s fame. When she was younger, she was sporty, playing hockey.

She never got to play on the international stage. She missed the Olympics because of the Second World War.

Instead she worked in the tobacco factory, married and raised a family. By the time she began drinking in her mid-40s, younger women were starting to enjoy a taste of freedom.

In contrast, she had three children under the age of five at a time of life when most women were becoming grandmothers.

On top of this, she was coping with the fallout of George’s fame and increasing notoriety.

If it was a fictional drama, it would be easy to create the turning points where a character becomes lost to alcohol.

But, of course, with a factual drama it’s not that simple. It’s about trying to understand real people, excavate real circumstances and map real relationships, seeing and living the world through their eyes.

And it seemed to me that if Ann did have a predisposition to alcoholism, this combination of circumstances might push her in that direction.

And then there was the other elephant in the room in writing this — dealing with Northern Ireland in the early 1970s.

I didn’t want to write a Troubles story. But at the same time I couldn’t ignore it.

When we first see George in the story, he’s being cheered on by people in Belfast who are thrilled that one of theirs is doing so well.

By the end of the story, a family member is identified as a Protestant and attacked purely because of her association with him. George and Ann’s legacy had to be set against the legacy of the Troubles.

At the time, though, to the world at large, George didn’t have a problem. He was just someone having fun, a young man sowing wild oats, not working his way to a serious drinking problem. One of the early decisions I took writing this was that in the film, George wouldn’t drink until it meant something emotionally.

It is his mother who sees that his problem is real, because she recognises herself in him.

The saddest thing of all is her recognition that, however much she might fight against this illness, the legacy might already have been passed to him — the very last legacy she would have wished for her son.

This was the story I wanted to try to tell, a family story that felt truthful and universal.

As I researched the piece I understood more and more how hard it must be for families to live with this illness.

Watching the person they know and love disappear a little bit at a time and being powerless to help is often the untold story.

And the Bests dealt with all of this under the constant gaze and reproach of the outside world. They had spent a lot of their lives living with the effects of George’s fame, with reporters knocking on their door, asking for quotes.

To me, the important thing in this film was to examine George’s legacy and to try to understand how he ended up where he was — and to be as truthful as possible about his life and that of his mother.

The family are working hard to make the George Best Foundation his legacy.

One of their aims is to raise public awareness of the effects of alcohol, and I hope that’s what this film does too.

We don’t give any simple answers on this but I think we do explore the notion that legacy might not be something you leave behind — it is also something you inherit.